1. Field of the Invention
The present invention relates to a switch connecting structure of a multifunctional electronic timepiece having an externally operated component.
2. Description of the Prior Art
In recent years, multifunctional electronic timepieces, such as watches provided with chronograph function and the like, have been commercially available in the market. Generally, in such a multifunctional electronic watch, a supporting plate is attached to substantially cap a planar portion of a basic circular movement, and is placed in a body of a watch case having substantially the same shape as the movement. In the switch connecting structure, depression of a push button, i.e. an externally operated component disposed at a predetermined position of the body of the case, causes a contact spring provided on the supporting plate to contact a switch contact on a circuit board, thereby electrically connecting to elements of electronic components provided in the movement.
Since the basic movement and the watch case are substantially in the same shape as described above, the pressing force of the push button is applied in the substantially central direction of the movement, and therefore the contact spring of the supporting plate is not worn off or deformed.
However, with the diversified customer needs in the market, there is a demand for watch cases in different shapes, such as a square case. Therefore, the basic circular movement is required to be placed in a square watch case rather than producing a new square movement.
FIG. 10 is a plan view illustrating an important part of a watch around a push button where a circular movement is placed in a square watch case. Referring to FIG. 10, a movement 1 includes a bottom plate, which is a base of the watch, receiving components supporting a train of various gears, and electronic components such as a quartz oscillator, electric elements, and an IC chip, mounted thereon. A circuit board 2 includes a wiring pattern for electrically connecting various elements of the electronic components, and a switch contact portion 2a provided on part of a side wall thereof. A supporting plate 3 is formed to substantially cap the planar portion of the movement 1. On the outer periphery of the supporting plate 3, one or more contact springs 3a of the same number as the push button 4 are formed at a position corresponding to the push button 4.
The push button 4 is provided to fit in the body of a square watch case 5 at a predetermined position. The basic circular movement 1 is attached to the square watch case 5 without any modification by placing the movement 1 capped by the supporting plate 3 into the body of the watch case 5. A stem 7 is used for common adjustment operation.
In the switch connecting structure described above, when a depressed portion 4a of the push button 4 is operated, an abutment portion 4b provided at a tip of the push button 4 presses down the contact spring 3a of the supporting plate 3 to bring a contact portion 3b at a tip thereof into contact with a switch contact portion 2a formed at the circuit board 2, thereby electrically connecting to various elements of the electronic components mounted on the movement 1.
However, in the conventional switch connecting structure described above, the pressing force of the push button 4 does not act in the central direction of the movement 1 because the basic circular movement 1 is placed in the square watch case 5 having a different shape. As a result, the depression portion 4b of the push button 4 and the switch spring 3a are brought into a point contact in a diagonal direction. Consequently, depression of the push button 4 results in abnormal wear-off or deformation of the contact spring 3a of the supporting plate. Therefore, repeated use of the push button 4 causes an unstable contact between the contact portion 3b of the supporting plate 3 and the switch contact portion 2a of the circuit board 2, possibly leading to a bad contact, abnormal wear-off or deformation. Further, as the distance between the push button 4 and the contact spring 3a is increased, the push button 4 having an extended longitudinal portion up to the abutment portion 4b is required. The push button 4 may be deformed during processing of the button, and extra material is required, leading to an increase in manufacturing cost.
An object of the present invention is to solve the above-described problems, and to provide an inexpensive switch connecting structure capable of avoiding abnormal wear-off or deformation of a contact spring of a supporting plate even if a movement in a basic shape is placed in a timepiece case having a shape different from the movement and a push button is repeatedly used.